Hey, I’m spawning a Niagara system but I can only see particles when they pass another actor. Could someone help me understand why that is?
Intended:
Actual:
Hey there @darthgrayter! Welcome back to the community! Are your particles meant to be occluded by those ball meshes? It just looks like they are below it from the screenshot. Are they being hidden while in front of it?
Hey @SupportiveEntity ! I understand the occlusion by the ball meshes, but I don’t understand why the particles aren’t showing up over the background, between the balls (e.g. the dark blue space part).
Ahhh I see what you mean. How is that background applied? Is this just a skybox or a plane/mesg in the BG or is this added in screenspace? Just trying to wrap my head around the scene to see if I can discern the interaction.
The ring is only visible on the edge of the occlusion for the spheres, kind of like it’s only receiving the (L) emission from them up close.
Yeah, so the background is just a plane mesh attached to the main character (ship). The material is a parallax effect combination of a few different textures.
Gotcha, so standard vertical shooter style. The Niagara system is much closer to the camera in world space right, but for some reason is being occluded by the plane in this case. Did you do any fancy material world position offsets that could make the plane verts render way closer to the camera?
Correct. I don’t think so, but let me double check. If I did do that, wouldn’t the other meshes be occluded as well? They’re all at the same z value
There doesn’t seem to be anything fancy with it. I’ve got an idea, in world space the particles are there and above it, so can they be seen if you hide the BG?
Is there any amount of distance back in the scene that then starts showing the particles or are they occluded indefinitely regardless of the plane Z pos?
Nope, looks like it’s occluded no matter the z pos.
Guessing this has to do with the way the orthographic camera handles depth. I was going to recommend sort order inside the system but unfortunately all that will do is change how it sorts inside the Niagara system not in the external scene. Try changing this setting in the rendering section of project settings and see if it reacts. I know this works for actors, but for Niagara systems I’ve never tested it.
Ok, interesting - unfortunately changing the sort policy only seemed to obscure even more / other particles
Having some trouble on my side reproducing the issue with the default top down project.
So I got a simple floating particle Niagara system to test it with the basic camera just changed over to orthographic.
It still respects Z depth so there must be something else interfering here.
Could either of these inner material functions be the culprit? I’m 99% certain the bg material is somehow the issue.
It looks like it’s just moving the UVs, which shouldn’t have that kind of effect. Translucency and orthographic view are the problem. During my tests I can properly recreate it now.
Looks like the particles are sorted behind the translucency just like yours. Now that I have a test bed I can play with it a bit to see if I can get a fix together.
EDIT:
We can sort by projected Z to correct it
I’m not certain the effects that will have on the rest of your translucent objects, but likely negligible if this functions as I expect.
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So changing the translucency sort policy didn’t do anything, but unchecking separate translucency makes the particles show up! Could this create issues for me in the future, though?
It depends on how you use transparency in the future. It’s not inherently a bad thing but it more or less renders all translucent shaders separately in a different rendering pass. This doesn’t mean much depending on if you’re using a bunch of post processing or anything for a really specific look. I’ve personally not had to use the setting since UDK and that was directly attached to the materials.
In short: I wouldn’t worry about it for now.
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Thanks @SupportiveEntity !! Your help was invaluable
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